The present invention relates to apparatus and methods for removal of emboli from within a vascular system. More particularly, the present invention provides a catheter having at least one blood intake port and an occlusive member through which venturi flow may be induced to remove emboli generated during an interventional procedure.
Today there is a growing realization that steps must be taken to reduce the release of emboli during interventional procedures such as stenting, atherectomy and angioplasty. These procedures generally present a high risk for the release of embolic material that may occlude downstream portions of the vascular bed and cause ischemia. The resulting ischemia may pose a serious threat to the health or life of a patient if the blockage forms in a critical area, such as the heart, lungs, or brain.
Several previously known methods and apparatus employ an aspiration catheter for removal of the clots and/or emboli. U.S. Pat. No. 5,749,858 to Cramer describes apparatus for aspirating a blood clot by connecting a central catheter to a suction device. The Cramer device attempts to reduce problems associated with clogging of the catheter by providing a replacement catheter. U.S. Pat. No. 5,938,645 to Gordon describes a thrombectomy device for sweeping arteries and removing emboli using suction.
Previously known suction systems have several drawbacks. First, when using an external suction source, such as those described in the above-mentioned patents, it may be difficult to regulate the aspiration pressure at the treatment site. If the amount of suction is too low for the circumstances, then embolic particles may be incompletely removed, thus resulting in further occlusive events.
On the other hand, the application of too much suction may cause a vessel wall to collapse or dissect, resulting in significant damage to the vessel wall and potentially jeopardizing the patient""s heath. In addition, an external suction device may induce a flow rate out of the vessel that cannot be sustained by the vessel wall for more than a few seconds, again potentially resulting in ischemia. Also, continuous use of an external suction device may result in excessive blood loss, requiring infusion of non-autologous blood. Finally, the use of an external suction device requires additional device complexity, including means to measure and regulate the applied suction.
Other methods for embolic removal have employed pressure gradients between the arterial system and the atmosphere to induce aspiration. For example, U.S. Pat. No. 4,921,478 to Solano et al. describes cerebral angioplasty methods and apparatus in which retrograde flow is induced through a catheter by leaving the proximal end of the catheter open to atmospheric pressure.
The foregoing solution to the problem of emboli removal, however, has several drawbacks which seem to have lead to abandonment of that approach. Chief among these problems is the inability of that system to generate flow reversal during placement of the guide wire and the angioplasty balloon across the stenosis. Because flow reversal does not occur until after deflation of the angioplasty balloon, there is a substantial risk that any emboli created during placement of the angioplasty balloon may travel too far downstream to be captured by the subsequent flow reversal, possibly causing further occlusive events.
In view of these drawbacks of previously known emboli removal systems, it would be desirable to provide apparatus and methods for removing emboli from within a blood vessel during an interventional procedure that reduces the volume of embolic particles released from the treatment site.
It also would be desirable to provide apparatus and methods for removing emboli that provide an appropriate level of retrograde flow at the treatment site, to direct dislodged particles into a catheter for efficient removal without damaging the treatment vessel.
It further would be desirable to provide apparatus and methods for removing emboli that utilize natural, physiologically regulated downstream flow from adjacent portions of the vascular system to achieve adequate retrograde flow in the treatment vessel.
It further would be desirable to provide apparatus and methods for removing emboli that eliminate the need for an external suction device to achieve retrograde flow, and to obviate the need to monitor and regulate such external suction device.
In view of the foregoing, it is an object of the present invention to provide a vascular device that overcomes disadvantages of previously known embolic removal systems.
It is another object of the present invention to provide apparatus and methods for removing emboli from within a blood vessel during an interventional procedure that reduces the volume of embolic particles that are released from the treatment site.
It is a further object of the present invention to provide apparatus and methods for removing emboli from a treatment site using an appropriate level of flow at the treatment site.
It is still a further object of the present invention to provide apparatus and methods for removing emboli that utilize natural, physiologically regulated downstream flow from adjacent portions of the vascular system to achieve adequate retrograde flow in the treatment vessel.
It is yet another object of the present invention to provide apparatus and methods for removing emboli that eliminate the need for an external suction device to achieve retrograde flow, and that obviate the need to monitor and regulate such external suction device.
These and other objects of the present invention are accomplished by providing a catheter having proximal and distal ends, and a lumen extending therethrough, an occlusive member at the distal end, and at least one blood intake port in a lateral surface of the catheter proximal of the occlusive member. In accordance with principles of the present invention, the catheter is configured to be percutaneously advanced in retrograde fashion through a host vessel until the distal end and occlusive member are positioned within the ostium of a treatment vessel or within the treatment vessel itself. The catheter may be used in conjunction with saphenous vein grafts, native coronary arteries, or other vessels. Upon deployment of the occlusive member, a portion of the antegrade flow through the host vessel will be diverted through the blood intake port, thereby inducing partial suction in the treatment vessel.
The diverted portion of the antegrade flow from the host vessel induces a controlled, physiologically regulated aspirating effect in the treatment vessel. The degree of suction induced in the treatment vessel may be controlled by adjusting the number or size of blood intake ports. A medical procedure then may be performed by inserting a therapeutic device, e.g., angioplasty catheter or embolectomy device, through the treatment lumen of the catheter to treat the lesion, while retrograde flow induced in the treatment vessel flushes blood containing emboli into the lumen of the catheter. The blood and emboli aspirated through the catheter may be filtered and then reperfused to the patient via a venous return system.